Food and Nutrition

Every day we eat food to live. Food is any substance that is consumed by animals to produce energy and aids in the body’s nutrition and growth. It is the animal or plant origin that contains proteins, lipids, carbohydrates, vitamins, and minerals. These components are known as essential nutrients. The nutrients are taken by the organisms, absorbed or digested by the cells to produce energy. Food and nutrition helps in maintaining the life form or stimulates body growth.

The body gets energy from the food. During the process of photosynthesis, solar energy is permanently embedded in the food. During respiration, the static energy is released in the form of heat energy or kinetic energy, which regulates all the metabolic functions of the body, such as respiration, excretion, nutrition, and other physiological functions, such as growth, movement, reproduction, etc. Therefore, every organism has to take food to live. So, the substance is consumed by the organisms to enhance the body’s growth, nourishment, energy production, and utilization are called food.

Nutrition is the process by which the living organisms assimilate food and uses it for growth and replacement of tissues and keeping the body healthy and strong. In this case, animals receive nutrients from the environment and fulfill the body’s energy. It also helps in preventing disease. Some essential nutrients  such as glucose, mineral, salts, vitamins, etc. maintain proper nutrition of the body

Role of Good Food

  • It helps to maintain body structure and growth.
  • It helps to maintain body temperature and executes the activity of the body.
  • It keeps the body diseases free.
  • It helps the sick person to cure.

Classification of Food

Food is divided into the following  two types based on the function of the food in the body:

1. Body ‍Supportive Food: Foods that help in the formation, growth, and production of energy are called body supportive foods. Important body supportive foods are carbohydrate, protein, and fat or lipid.

2. Body Maintaining Food: Foods that protect the body from infection, which are not contributing to energy production, is called body maintaining food. Significant body maintaining foods are vitamins and minerals.

Based on the maintenance of the body, food can be divided into the following three types:

1. Energy Producing Food: The primary role of these foods is to keep the body fresh and functioning by producing energy and heat. Internal activities of the body, such as breathing, cardiovascular, and other body functions, digestion, excretion, and all events in daily life, etc. require energy. In this case, the body gets energy from these types of food.

The most important energy-producing foods from which body gets energy are:

Grain-based food: rice, wheat, corn, maize, etc.

Root-based food: Potatoes, sweet potatoes, cassava, etc.

Oily or fatty foods:  All kinds of oils, ghee, meat fats etc.

Sugar, and sweets, etc.

2. Body Building, Growing, and Repairing-based Foods: These diets are mainly used in the body to create or maintain body structure, enhance the body, and repair the body. These foods are derived from animal and plant sources:  Eggs, milk, fish, meat, etc. while animal sources are eggs, milk, fish, meat, etc.

Food derived from plants sources: All kinds of pulses, peas, bean seeds, jackfruit seeds, nuts etc. are notable.

3. Disease Resistant food: The main role of these diets is to increase the immune system of the body, protect the body from various diseases or illnesses. Disease-resistant foods include Colored vegetables, Fruits, etc.

Basic Food Types

The primary foods are divided into the following six types:

1. Carbohydrates

Carbohydrates are composed of three components: carbon, hydrogen, and oxygen. In this case, the ratio of hydrogen and oxygen is 2: 1. respectively. Molecular symbol of carbohydrates: Cn(H2O)n. For example, glucose(C6H12O6), sucrose(C12H22O11), etc.

Sources: rice, wheat, corn, potatoes, oats, beets, carrots, dates, grapes, apples, Vegetables, watermelons, ripening fruits such as Mango, banana, oranges, milk and liver, etc.

Classification of Carbohydrates

Carbohydrate is divided into the following three types based on the presence of one or more units of simple sugar:

1. Monosaccharides: The sugars that are made up of only one molecule of carbohydrate, called monosaccharides-for example, glucose, fructose, and galactose.

2. Disaccharides: The sugars that makeup two molecules of carbohydrates, called disaccharides—for example, sucrose, lactose, and maltose.

3. Polysaccharides: The sugars that are made up of more than two to many molecules of carbohydrate, called polysaccharides, for example, starch, glycogen, and cellulose.

Nutritional Importance of Carbohydrates

  • The main function of carbohydrates is to increase the functioning of the body and the production of heat energy.
  • It helps to eliminate the constipation of the body.
  • Glycogen is stored in the liver and muscles, which turn into glucose when needed
  • Glycogen helps to maintain the amount of glucose in the blood.
  • It helps to prevent the breakdown of proteins for energy.
  • Carbohydrate helps to regulate the metabolic process.
  • Carbohydrates form the important components of nucleic acid, such as pentose sugar(ribose, deoxyribose).
  • It can perform physiological anticoagulants such as heparin.
  • It helps break down fatty acids and prevents ketosis.

2. Proteins

Protein consists of carbon, hydrogen, oxygen, and nitrogen. Sulfur and phosphorus are also often present in proteins. Protein-molecules are composed of numerous amino acids. Among amino acids, the following essential  nine amino acids must come from food, include:

  1. Histidine,
  2. Isoleucine,
  3. Leucine,
  4. Lysine,
  5. Methionine,
  6. Phenylalanine,
  7. Threonine,
  8. Tryptophan, and
  9. Valine


Animals-based proteins are found in fish, meat, milk, eggs, and plant-based proteins such as pulses, soybeans, beans, wheat, etc. Animal-based amino acids are the first class of amino acids or proteins since they contain almost all types of essential amino acids.

Classification of Protein

Proteins can be mainly divided into the following three categories:

1. Simple Proteins

Proteins that are not attached to any other ingredient are called simple proteins. Examples: albumin, globulin, protamine, histone, gliadin, glutelin, etc.

2. Conjugated  Protein

When simple proteins are linked to other non-protein substances, they are called conjugated proteins. Examples: hemoglobin, hemocyanin, phosphoprotein, lipoprotein, etc.

3. Derived Proteins

The proteins are derived through partial or complete hydrolysis from simple or conjugated proteins, known as derived protein, for example, peptone, peptide, etc.

Nutritional Roles of Protein

  • Protein plays an important role in the body’s growth, cell structure, and repair
  • They produce heat energy.
  • They help to produce body enzymes, hormones, etc.
  • Protein performs the essential functions of essential amino acids.

It is noted that the combustion of 1 gram of protein molecule produces 4.1 kcal of heat energy. An adult person needs about 100-150 grams of protein per day.

Protein deficiency Symptoms

  • Loss of muscle mass;
  • Reducing immunity;
  • Weakening of the heart;
  • Creating respiratory problems;
  • Low growth and a weakened immune system are due to insufficient protein
  • In many cases, excess protein leads to liver problems and weight gain.

3. Lipid

Lipids or fats are made up of carbon, hydrogen, and oxygen. In this case, the oxygen ratio is lower than the carbohydrate, and here, hydrogen and oxygen are not present in the 2 : 1 ratio like a carbohydrate. Fat is actually an ester made up of acid and glycerol.

Lipid is insoluble in water but soluble in ether, alcohol, and chloroform. It constitutes the animal and plant cells, together with carbohydrates and proteins. It is actually an important part of living cells.  Examples: Cholesterol and triglycerides.


Plant-based lipids are nuts, coconut, mustard seeds, sesame seeds, cotton seeds, etc. and animal-based pilids are butter, ghee, fats, etc.

Classification of Lipid

Lipid is generally of two types, namely:

1. Simple Lipid or Fat:  Lipid  that is not linked to any other substances is called simple lipid. For example, wax, fats, etc.

2. Compound Lipid: When simple lipids are associated with any other substances, then they are called compound lipid, for example, phospholipid, glycolipid, amino-lipid, etc.

Nutritional Roles of Lipid:

  • The main function of lipids in the production of heat energy.
  • It regulates the body’s temperature by making insulation the body.
  • It is stored as a source of food for the future.
  • It helps to dissolve fat-soluble vitamins such as A, D, E, K, and helps absorb them.
  • It helps to secretion of bile from fatty liver and pancreatic juice from the pancreas.
  • It helps to the lubricated anus to drain feces.
  • Vitamin D, hormones like estrogen and testosterone are produced from the lipid-like cholesterol.
  • Different lipids such as diacylglycerol, sphingosine ceramides, etc. serve as a platelet-activating factor to regulate the intracellular processes.
  • It also takes part in cell division.
  • Lipid helps to protect internal organs.
  • It can be noted that 9.3 kcal of heat energy produce from 1 gm of fat. An adult person needs about 50 grams of lipids every day.

4. Vitamins

Vitamin is a special organic component that helps the nourishment of the body and increases the immune system.   It is an essential micronutrient that requires small quantities in the body of organisms. It is important for the appropriate functioning of the body’s metabolism. The organisms cannot synthesize these essential nutrients. Hence it must be supplemented through the diet from outside.

Classification of Vitamin

Vitamins are divided into two groups, according to solubility, namely:

1. Fat-Soluble Vitamins:  Vitamins that are dissolved in oils or fats are called fat-soluble vitamins, for example, Vitamin A, D, E, K.

2. Water-soluble vitamins: Vitamins that are dissolved in water are called water-soluble vitamins, for example, Vitamin B-complex and Vitamin C.

Sources of Vitamins

Milk, Eggs, Fish, Meat, Animals, Oil, Butter, Vegetable Oil, Almonds,  Rice,  white Flour, Pea, Beans, Carrots, Palanquin, Tomatoes, Cabbage, Fruits like mango, apple, etc. are the main source of vitamins. Most of the vitamins are found in milk, eggs, spinach, tomatoes, beans, bananas, apples, etc.

The sources of vitamins A and D are cod, halibut liver, liver oil, butter, milk, eggs, carrots, cabbage, etc. Coconut, mustard oil, kernel seeds, cotton seeds, etc., contain vegetable fats and butter, ghee, fats, etc. contain animal fats.

Nutritional Roles of Vitamins:  Generally, balanced food helps to provide sufficient vitamins to the body. Old-aged people (50 years and more) requires enough vitamin B12.

The Following Table Shows the Water-Soluble Vitamins, their roles and Sources

Vitamins Roles Sources
Vitamin B1 (Thiamine)
  • It requires producing energy for metabolism.
  • It helps to nerve functioning.

They are available in all nutritious foods in reasonable amounts: Meat, whole-grain cereals, legumes, nuts, and seeds, or breads.

Vitamin B2 (Riboflavin)
  • It is an important vitamin that is needed for normal vision.
  • It functions for energy metabolism.

It is found in leafy green vegetables, whole-grain, cereals bread,  milk, and milk products, etc.

Vitamin B3 (Niacin)
  • It keeps skin healthy and helps in the digestion and nervous system.
  • It is also required for the metabolism of energy.

It is found in animal-based food like fish, meat, and poultry. Plant-based foods such as

whole-grain, cereals, mushrooms, asparagus, various leafy vegetables,

peanut butter, etc.

It is also rich in bread.

Vitamin B5 (Pantothenic acid)
  • It helps to produce red blood corpuscles (RBC).
  • It also produces sex and stress-related hormones.
  • It maintains a healthy digestive tract.
  • It helps to synthesize cholesterol.

It is widespread in both plants, and animal- based foods such as cereal grains, meat, eggs, and milk, vegetables, legumes.

Vitamin B7 or H (Biotin)
  • It helps to metabolize protein, fats, and carbohydrates.
  • It can convert your body food into energy.
  • It helps the women who are pregnant and breastfeeding to her child.
  • It is important for keeping healthy hair, skin, and nails.t

It is widely found in the following foods: Meats, liver, kidney, egg yolk, cheese, yeast, leafy green vegetables, peanuts, soybeans, mushrooms, cauliflower, nuts, and nut butters.

Vitamin B6 (Pyridoxine)
  • It helps to produce RBC.
  • It helps in protein synthesis.
  • It performs to make several neurotransmitters in the brain.
  • It is very important for pregnant women and infants.
  • It is used in the development of the brain and support the immune system.
  • It controls the amino acid homocysteine in the blood along with other vitamins such as pyridoxine.

Chick peas, beef liver, fish meat, banana, tofu, milk, avocados, brown rice, potato, carrots,  soybeans, whole grains, spinach, hazelnuts, fortified cereal, seeds, and different fruits.

Vitamin B9 (Folic Acid, Folate)
  • Folic acid helps to produce RBC.
  • It is important for making DNA.
  • It helps to develop a nural tube in the brain of the baby.
Legumes (Beans)

, leafy green vegetables (spinach), and seeds, Citrus fruits (orange juice), and liver,  cereals, Pasta, bread,

Rice, etc.

Vitamin B12 (Cobalamin)
  • It needs to produce proper red blood corpuscles.
  • It performs a neurological function, and DNA synthesis.
  • It also performs as a cofactor for methionine synthase.
Dairy milk products, eggs, fish, meat, and poultry, Seafood, milk.
Vitamin C (Ascorbic acid)
  • It acts as antioxidants.
  • It is important for the immune system.
  • Vitamin C helps to protect cells and make s them healthy.
  • It maintains healthy skin, bones and cartilage, and blood vessels.
  • It also helps in wound healing.

Good sources of vitamin C are  fruits (citrus fruits, mangoes, strawberries, papayas,, kiwifruit) and vegetables such as cabbage family,  red and green peppers, tomatoes, potatoes, lettuce, blackcurrants,  broccoli, brussels sprouts,etc,.

Fat-soluble vitamins are stored up in the cells of the body. If you take a balanced diet then they get enough fat-soluble vitamins.  The following table shows the sources and functions of fat-soluble vitamins.

Vitamins Roles Sources
Vitamin A

(Retinol: Animal-based; Beta-carotene: Plant-based)

  • It is required for healthy skin, bone and tooth growth.t
  • It helps in the vision, and mucous membrane.
  • It also helps in the immune system against diseases.
  • Vitamin A acts as an antioxidant, and prevents cell damage and many other tissues.

It is found in both plant and animal-based foods. Animal sources are

fortified milk, cream, cheese, butter, eggs, liver, kidneys,  halibut fish oil,

Plant sources are leafy, dark green vegetables, dark-orange fruits such as  apricots, cantaloupe and other vegetables such as carrots, squash, winter pumpkin, sweet potatoes,etc,.

Vitamin D
  • It is very important for maintaining teeth and bones.
  • It prevents various diseases.
  • It performs lung function and cardiovascular health.
  • It helps in the immune system, nervous system and brain.
  • It controls the level of insulin and supports diabetes management.
  • It helps in proper calcium absorption in bones.

Egg yolks, liver, fatty fish such as salmon, mackerel, and tuna, fortified milk, cheese, beef liver, egg yolks,  fortified cereals, and juices. You can also get vitamin D from sunlight directly through the absorption of skin.

Vitamin E
  • It acts as an antioxidant to protect cell walls from the damage.
  • It helps in bone metabolism and heart health.
  • It also helps in energy production in the mitochondria of cells.

Plant sources are leafy green vegetables such as kale, collard greens, and spinach, cauliflower and cabbage,  green vegetables such as broccoli, Brussels sprouts, green leaf lettuce, romaine lettuce asparagus, and cereals;

Animal sources are meats, liver, fish, and eggs.

5. Mineral Salt

Our body also needs the most important inorganic compounds, known as sodium chloride (Nacl) or salt. It is essential for animal life but is toxic to most terrestrial plants. Salt is considered one of the basic elements which are used throughout the world in food preparation.

Besides, the body also needs other inorganic minerals that we get from the water and soil. It is absorbed by the plants and eaten by the animals.  The body requires sufficient amounts of some important minerals such as calcium, which helps in growth and making the body healthy.

Iron, chromium, iodine, zinc, copper, selenium, etc are known as trace minerals because our body needs only minute quantities each day.

The following table shows the some important minerals, their roles, sources and daily requirements:

Minerals Roles Sources Daily requirement
  • In combination with phosphorus, calcium builds and strengthens the body’s structure, bones, and teeth.
  • It is required in the formation of every living cell.Element
  • It helps to produce blood-clotting material.
  • It helps in the contraction, propagation and making pulsation of the heart.

Animal sources are small shrimp, small fish, soft bones, milk, and milk products.Vegetable sources ares pulses, spinach, greens vegetables, etc,.

• 450 mg (for adults)• 500-600 mg (for baby)• 650 mg (for teenage)• 1100 mg (for pregnant)• 1100 mg (lactateting mother)

  • It combined works with calcium and builds and strengthens the bones and tooth tissue.
  • It helps in the metabolism of carbohydrates and fats to produce heat and energy.
  • It is an important part of the cell’s nucleic acid and cytoplasm.

Animal sources are fish, meat, milk, eggs, cheese, etc,

Vegetable sources are  nuts, pulses, and grains.

• 800 mg
  • It is required to produce fatless muscles of the body.
  • It maintains the normal movement of the muscle.

Animal sources are fatless meats and milk (but almost all foods contain potassium)

•2.5 mg (for adults)

  • It helps to produce hemoglobin of blood.
  • It uses in the oxidation-reduction process as part of numerous enzymes.
  • Iron is needed for the electron-transport system in biochemical processes.

Animal sources are   meat, liver, eggs, catfish,  drying fish.

Plant sources are green mango, blackberry, and , various vegetables.

• 09 mg (for adults)• 10 mg (for younger boys and girls)• 18 mg (for teens)• 24mg (for teenage)• 28 mg (for adult women)• 33 mg (for pregnant)

  • It is essential for the production of thyroxine hormone.
  • It is essential for physical and mental growth.

Animal sources:  marine fish (fresh/dried).

Plant source: marine weedsIodine mix salt

•150 microgram
  • It helps in enzymatic reactions.
  • It boosts up make the immune system strong.
  • It enhances protein and DNA synthesis.
  • It helps in body growth and development.

Shellfish, Meat, Poultry, Fish, Legumes such as Chickpeas, beans, lentils, black beans, etc. Nuts and seeds, Dairy products such as milk, yogurt and cheese, Eggs, Whole grains such as Oats, brown rice, etc.

Vegetables such as Mushrooms, asparagus, and beet, spinach, etc

•11 mg (for adult men)

•8 mg (for adult women).

 •11-12 mg

(for pregnant and breastfeeding women)

6. Water

Water is an important ingredient in the food. Water is essential for the human body. Body composition and internal functioning cannot continue without water. 60-70% of our body weight is water.  Water is important to form the muscles of every organ, nerve, teeth, bones, etc. All of the physiological processes and the formation of cells are not possible without water.

  • Water helps in any chemical changes in the human body.
  • It helps in food digestion, absorption, accumulation, and also helps in eliminating faces.
  • It helps to maintain body temperature.
  • It performs to convey nutrients from one place to another.
  • It performs to convey nutrients from one place to another.

Criteria of Balanced Diet

  • Balanced diets mean they contain the proper amount of nutrients for the body.
  • The balanced diet should include the appropriate amount of strong, body-enhancing food that can fight against harmful and pathogenic agents.
  • A balanced diet can vary depending on age, function, gender, and physical condition.
  • In addition to dietary ingredients for a healthy body, plenty of fats should be included in the daily diet list. Besides, every people should take safe drinking water.
  • In the daily diet list, there should be no food that contains harmful chemicals.
  • A balanced diet does not just mean expensive food, but you can also be made it using cheap food items.

Concluding Remarks

The body needs sufficient nutrients to make energy, which is essential for keeping various systems working properly. It also helps in proper growth and maintains the body’s tissues. All these nutrients come from the food taken by the organisms. Our body needs a new supply of nutrients every day. The most important nutrients are water, carbohydrates, proteins, and fats. Besides different minerals and vitamins play an important role as micronutreints maintaining good health.

Food and nutrition make fuel providing energy to the body. Pregnant women and adult people over 50 need sufficient vitamins and minerals such as calcium, and iron as a healthy diet.  In this case, fruits, vegetables, whole grains such as brown rice, wheat play as good part in our daily diet. Besides, non-fat or low-fat dairy products, lean meat, eggs, legumes, beans, seafood, soy products nuts, etc. make good nutrition, especially for the adult people.